Subject: Re: [Megaco] Continuity tests

From: Vance Shipley <[email-masked]>
Date: Tue, 4 May 2004 13:42:35 -0400

On Fri, Apr 30, 2004 at 10:39:14AM -0400, Aleksandr Ryabin wrote:
}  
}  There could be "dumb" switches in the middle of the path
}  (for example DACS) which are not capable of any testing/signalling.
}  Their only role is to split/redirect links and as such the nature
}  of a circuit can change, and thus the type of COT test.

The reason COT was included in ISUP is because of the possible
presence of DSO level DACS.  If all interconnections were at the
E1 or DS1 level you would need only to monitor alarms and performance 
reports at the span level to know about the integrity of those
circuits.  If the bearer channels have been processed through a
DSO DACS or something similiar you can't use the span level 
alarming/reporting.  Even more importantly the likelyhood of a 
problem is increased.  A common problem is that the mapping was
done in error.  COT testing tests this by requesting a loopback
and checking that what is sent is received while the loopback is
in place.

The COT request and response is binary.  There is no need or
opportunity to request the type of test as the type of test is
provisioned with the circuits. 

	-Vance

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From: Vance Shipley <[email-masked]>
Date: Tue, 4 May 2004 13:42:35 -0400

-Vance

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From: Aleksandr Ryabin <[email-masked]>
Date: Tue, 04 May 2004 15:41:36 -0400

ISUP COT request and response are coming to/from MGC and not to/from MG.
Yes ISUP does not have a need, or opportunity to request the type of test,
but MGC does.

My point was that the type of test is provisioned with MGC and not MG
as MGC and not MG is an ultimate entry that has information of where
MG circuit (ds0) is eventually connected to. As such MGC has to be
able to tell MG which COT test to perform.

         Aleks

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From: Aleksandr Ryabin <[email-masked]>
Date: Tue, 04 May 2004 15:41:36 -0400

Aleks